2008 Diesel, poor mpg around town

Questions specifically about a Diesel powered C3 (usually engine or fuel related problems)
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My Name: saad-jay

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Posts: 16
Joined: Mon Oct 15, 2012 1:56 pm

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I have been useing shell diesel for the few months with been getting good mpg. Around 50 around town now my mpg has dropped to 31 mpg. My car is due for a service and look at the oil for my car from this site. Im using TOTAL QUARTZ 9000 5W/40. When i first got the car it was doing 70 mpg. What can i do to improve it?
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My Name: Arfur Dent

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Posts: 3410
Joined: Sat Jul 23, 2011 3:47 pm
Model: C3 2002-2005, Original shape model
Year: 2002 (52)
Engine Size: 1.4 (16v)
Fuel Type: Diesel
Mileage: 100000
Trim Level: Exclusive
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: RHD (UK)
Engine name: DV4 16-valve diesel (90 PS)
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When i first got the car it was doing 70 mpg. What can i do to improve it?
  • Check the tyre pressures, under inflated tyres increase fuel consumption.
  • Remove excess weight - is the boot full of things?
  • Improve the driving style - probably not for you as I don't expect your style has changed, but maybe the route you drive has?
  • But it could all be down to the measuring. How do you measure the consumption?

If you have changed the way you measure, this could introduce a different error.


A good way to measure fuel consumption.
Fuel up to full (first click at the pump), note the mileage, then next time you fill up with fuel, note the mileage and the quantity of fuel required to the first click again. You can then get a good calculation of distance travelled on that quantity of fuel. This is repeatable and doesn't rely on any computer.
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My Name: saad-jay

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Posts: 16
Joined: Mon Oct 15, 2012 1:56 pm

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Hi i use the on board trip computer for the mpg. My root has changed but its because i go a short way. My car is not of junk so my boot is empty.
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My Name: Arfur Dent

Guru
Posts: 3410
Joined: Sat Jul 23, 2011 3:47 pm
Model: C3 2002-2005, Original shape model
Year: 2002 (52)
Engine Size: 1.4 (16v)
Fuel Type: Diesel
Mileage: 100000
Trim Level: Exclusive
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: RHD (UK)
Engine name: DV4 16-valve diesel (90 PS)
Has thanked: 305 times
Been thanked: 119 times

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Hi i use the on board trip computer for the mpg.
That will be the reason I guess. Its not that your MPG has changed, its something to do with the way the MPG is calculated in software.

If you use the method I described above for accurate MPG measurements and you will get repeatable and consistent MPG readings.
A good way to measure fuel consumption.
Fuel up to full (first click at the pump), note the mileage, then next time you fill up with fuel, note the mileage and the quantity of fuel required to the first click again. You can then get a good calculation of distance travelled on that quantity of fuel.
You can add an avatar to your account - Avatar or change your vehicle details - Car Bio or even add a signature to your posts - Signature. But this is not all you can do in the User Control Panel :)
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